In the current year we have set four (4) goals: Determine structure activity relationship of cannabinoids on L1210 DNA synthesis. 2. Determine the incidence of double strand breaks in L1210 DNA. 3. Determine the effects of delta 9-THC on DNA polymerase. 4. Clarify the effects of cannabinoids on enzyme induction. In order to accomplish the first goal, we performed dose response experiments on a wide variety of cannabionoids in mice carrying L1210 murine leukemia, and measured tumor DNA synthesis. We, also, contrasted these effects with those we observed on tumor cell respiration. To accomplished our second goal we analyze neutral sucrose graidents of DNA from L1210 cells. DNA polymerase assays carried out for out third goal were performed on L1210 nuclei. Very quickly we found out that there was no effect on either L1210 polymerase or THC, neuroblastoma or glial cell nuclear polymerase. We then, also, analyzed mitochondrial DNA polymerase. In studies on enzyme regulation, we investigated the effects of delta 9-THC on the response of tyrosine aminotransferase to inducers other than hydrocortisone. We, also, investigated the effects of other cannabinoids on tyrosine aminotransferase induction by hydrocortisone. BIBLIOGRAPHIC REFERENCES: Marvin A. Friedman, Inhibition of arylhydrocarbon hydroxylase induction in BALBC mouse liver by delta 9-tetrahydrocannabinol. Res. Comm. in Pharmacol. and Chem. Pathol. 15:541-552, 1976.